1170946 - Pressing Measure in quick succession drastically increases the occupied memory.

Status: RESOLVED WONTFIX

(Toolkit :: about:memory, defect)

Description

[Catalin Varga [QA][:VarCat]]

Environment:

FF 41
Build Id: 20150602055237
OS: Win 7 x64, Mac Os X 10.9.5

STR:

1. Start Firefox and go to about:memory
2. In quick succession press Measure.

Issue:
After each time Measure is pressed the occupied  memory is increased by 10-30 MB.

Note:
This is reproducible also on FF 38, 39 and 40.

Comment 1

[Andrew McCreight [:mccr8]]

To some extent, that is expected, because generating the page itself takes up some memory. When you click the button again, it throws out the old page, and then it takes a few seconds for the garbage collector to run and free the old page. njn did some work to reduce the amount of memory about:memory uses, but that was a while ago. Getting two successive about:memory reports would be a little more information, if somebody wanted to look into reducing the memory again.

Comment 2

[Nicholas Nethercote [inactive]]

McCreight is correct, and this is expected behaviour. There are *many* DOM nodes in about:memory and when you re-measure it throws out all the old ones and has to create a lot of new ones. After a while GC kicks in and the memory usage drops again.

Clicking "measure" repeatedly isn't a terribly useful thing to do, so IMO this isn't a problem that needs fixing.